Hypereosinophilic syndrome presenting as cutaneous necrotizing eosinophilic vasculitis and Raynaud's phenomenon complicated by digital gangrene.

Cutaneous necrotizing eosinophilic vasculitis is a recently identified type of vasculitis that is characterized by an eosinophil-predominant necrotizing vasculitis affecting small dermal vessels. Clinically, it presents with pruritic erythematous and purpuric papules and plaques, peripheral eosinophilia and a good response to systemic steroid therapy. This vasculitis can be idiopathic or associated with connective tissue diseases. Although the pathogenic roles of eosinophil-derived granule proteins and interleukins have been documented in diseases associated with eosinophilia, a role of CD40 (a glycoprotein of the tumour necrosis factor receptor superfamily) has rarely been described. We describe two patients with idiopathic hypereosinophilic syndrome (HES) presenting with multiple erythematous patches and plaques on the lower extremities and Raynaud's phenomenon. They satisfied the criteria for the diagnosis of HES by clinical and laboratory investigations. Histopathology of the cutaneous lesions revealed prominent eosinophilic infiltration with local fibrinoid change in vessel walls in the dermis and subcutis. Immunohistochemical detection of CD3, CD4, CD8 and CD40 was performed. Infiltrating eosinophils were strongly stained by anti-CD40 monoclonal antibody. One patient improved with prednisolone, pentoxifylline and nifedipine, without recurrence. The other patient initially improved with steroids, but after self-withdrawal of steroid developed digital ischaemia that evolved to severe necrosis and required amputation. Cutaneous necrotizing eosinophilic vasculitis, Raynaud's phenomenon and digital gangrene may develop as cutaneous manifestations of HES. CD40 may play a part in the pathogenesis of eosinophilic vasculitis in HES.